Technique for Safety Design Improvement of Grounding System by Compression Ratio Methods in Metropolitan Electricity Authority's System
Att Phayomhom, Somporn Sirisumrannukul, Boonserm Ainsuk · 2018
This paper presents a touch voltage reduction technique for uniform and two-layer soil by applying grid compression ratio. The design of ground grid is directly involved its maximum touch and step voltage produced for a given GPR. These two parameters are analyzed to ensure that they conform to the IEEE Std 80-2013. It is found that, for a given GPR, the maximum touch and step voltages of a rectangular ground grid, regardless its compression ratio, are lower than a square one. This implies a rectangular grid is safer than a square one. The shape of ground grid is therefore one of the factors of interest in grid design, particularly when a new substation is being constructed near another one that is still energized. When there is a difference in GPR, the touch voltage can be made worse by the two unconnected grids, and may harm personnel and damage sensitive equipment.